possible extent. The hands must be protected in accordance with the same principles, and the head. I used a R.N.A.S. pattern flying helmet and found it most satisfactory. Helmet and snow-glasses should completely cover the head and face, leaving no skin exposed. Boots were a source of trouble to all, but fortunately we had so many different designs which we could test out thoroughly that we are now able to form a very shrewd idea as to which kind is the most suitable. Leather conducts heat too well for reliance to be placed upon it for the preservation of warmth. The uppers of the boots should be of felt, strengthened where necessary to prevent stretching, by leather straps covered by duroprened canvas. Toe and heel caps must be hard and strong, and the former especially should be high, so that the toes are given plenty of room. The sole of the boot should be composed of a layer of thin leather attached to a layer of three-ply wood, hinged in two sections at the instep. A thin layer of felt should form the inside of the sole. The boots should be large enough to accommodate in comfort two pairs of thick socks, or, even better still, two pairs of thin socks and one pair of thick socks. Nails used in the boots should penetrate through the leather into the three-ply wood, but not through the latter. In conclusion, I should like to thank the Governing Body of the Imperial College of Science and Technology for granting me the necessary leave to enable me to take part in the 1922 Mount Everest Expedition, and also for granting me facilities for carrying out a considerable number of investigations in the laboratory of the Department of Chemical Technology upon questions relating, amongst others, to oxygen equipment, fuels, and vacuum flasks. These last were required in order to enable us to keep foods liquid at heights over 23,000 feet, and the flasks obtained on the market proved quite useless for this purpose in view of the fact that they had not been sufficiently well evacuated. ------------------------------------------------------------------------ THE THIRD ATTEMPT By GEORGE LEIGH-MALLORY ------------------------------------------------------------------------ CHAPTER X THE THIRD ATTEMPT